Some Features of High-temperature Superconductivity on Flat Bands

In this letter, we examine how the presence of flat band leads to the formation of a high-temperature superconductor even in the case of repulsive pairing interactions. We also show that in the case of flat bands, the high-temperature superconducting state deforms the flat band, tilting it and making the effective mass finite. As a result, neither the superfluid weight nor the supercurrent disappear. Our results are in good agreement with experimental data.